Sewing needle clamp



Jan. 4, 1955 R. E. JOHNSON SEWING NEEDLE CLAMP Filed July 25, 1951 IN VEN TOR.

l hw l l'a ATTORNEY WITNESS 7/ /doa w United States Patent O 4' SEWING NEEDLE CLAMP Ralph E. Johnson, Mountainside, N. J., assignor to The I Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey This invention relates to a sewing machine and more particularly to a needle-clamp for attachinga sewing needle to a needle-bar.

An object of the invention is to provide a clamp for securing a sewing needle to a needle-bar.

A further object of the invention is to provide a needle-clamp which will receive the sewing needle in the correct sewing position only.

In the drawings, Fig. 1 is a view in front elevation of the needle-clamp installed in a sewing machine.

Fig. 2 is a vertical sectional view of the device.

Fig. 3 is an enlarged view, partly in section taken on line 3-3 of Fig. 1.

Fig. 4 is a front elevation of the lower end of the needle-bar.

Fig. 5 is a side elevation, partly in section, of the lower end of the needle-bar.

Fig. 6 is a perspective view of the needle clamping gib.

Fig. 7 is a view in front elevation of the sewing-needle shank showing the sectional shape of the shank.

Fig. 8 is a view similar to Fig. 3 of a modification of the invention.

Fig. 9 is a view in front elevation of the substitute needle with the shank in section and used in the modified form of the invention.

Referring more particularly to the drawings, a needlebar 10 is mounted in a sewing machine head 11 for reciprocatory movement. The lower end of the needle-bar 10 is formed with a needle-receiving slot 12 having a flat bottom 13 and parallel side walls 14. Axial motion of a needle 15 in the slot 12 is limited in one direction by a transverse pin 16 fastened in the needle-bar 10 and protruding into the slot 12. A clamping band or ring 17 encircles the lower end of the needle-bar 10 and carries a thumb-screw 18 threaded into the clamping band 17 opposite the slot 12. The needle-bar 10 is provided with a cylindrical recess 19 intersected by the slot 12 and the band 17 is provided with a cylindrical aperture 20 alined with the recess 19 to receive a cylindrical needleclamping gib 21. To permit assembly of the clamp, a channel 22is formed in the needle-bar 10 extending from the lower end of the needle-bar 10 to the aperture 19. A securing screw 22' holds the band 17 in place on the needle-bar 10.

The sewing needle 15 is of the usual, well-known type having a shank 23 formed as a slab-sided right circular cylinder and having an eye 24 formed at the needle-point. It should be noted that the cross-sectional height h of the needle-shank 23 is the minimum diametral dimension of the shank while the width a is the maximum diametral dimension. The slot 12 is just wide enough to receive the needle-shank 23 with its slabbed side 25 properly positioned against the flat bottom of the slot 12. The cylindrical portion of the needle-shank 23 is received in a groove 26 in one end of the gib 21. The groove 26 is semicircular in cross-section to conform to the cylindrical portion of the needle-shank 23. A positioning guide finger 28 carried by the gib body portion is received in the slot 12 and prevents rotation of the gib 21 in the apertures 19and 20. The gib body portion also carries a thread guide 29 which extends below the end of the needlebar 10 to control the needle thread 30. It should be noted that a portion of the thread guide 29 lies in the same plane as the guide finger 28. In order to prevent insertion of the needle in any position other than the correct position, the maximum distance between the bottom of the slot 12 and the gib measured perpen- 2,698,589 Patented Jan. 4, 1955 dicular to the bottom of the slot is less than'the width or maximum diametral dimension d of the needle shank 23. The guide finger 28 and thread guide 29 are so placed relative to the grooved face of the gib that when the gib 21 is retracted and the guide finger 28 and the thread guide 29 engage the inner cylindrical surface of the clamping band, the desired maximum distance between the bottom of the slot and the gib is obtained. The total motion permitted the gib 21 from its' needle-clamping position to itsfully retracted position is less than the difference between the maximum and minimum diametral dimensions d and h.

Assembly of the needle-clamp is efiected by inserting the gib in the aperture 20 in the band 17. The band is then slipped on the end of the needle-bar with the grooved end of the gib 21 positioned in the channel 22. When the gib 21 is positioned in the aperture 19, a few turns of the thumb-screw 18 forces the grooved end of the gib into the aperture 19 beyond the bottom of the channel 22. The gib then engages both the band 17 and the needle-bar 10 and prevents removal of the band 17. The screw 22' is then inserted and tightened.

From the foregoing description, device will be readily apparent. In any sewing machine, it is essential that the point of the needle must always pass a certain fixed distance away from the loop-taker (not shown). In order to assure passage of the needle at this fixed distance from the loop-taker, the point of the sewing needle must always hear a certain fixed relation to the needle-bar. It is standard practice in the art for the shank of a sewing needle to be provided with a slabbed side 25 which lies in a plane a fixed distance from the needle point. The same fixed distance is maintained regardless of the size of the needle. By placing the slabbed side 25 of the needle-shank against a flat surface on the needle-bar, the correct distance between the needle and the loop-taker (not shown) will always be correctly maintained. If, however, the needle is attached to the needlebar, in any other position, poor stitching will result, since the correct distance is not maintained.

In the instant needle-clamp, it is impossible to insert the sewing needle in any position other than the correct position. Since, even with the thumb-screw 18 removed, the gib 21 can move back only until the members 28 and 29 contact the inner surface of the clamping band 17, the needle can be inserted in only the correct position with the slabbed side of the needle adjacent the bottom of the slot. The dotted line position of the needle 15 in Fig. 3 indicates the condition obtained if an attempt is made to insert the needle backwards. In such an event, with the curved portion of the needle-shank positioned against the bottom of the slot 12, the gib cannot be withdrawn far enough to permit the slabbed side 25 of the needle to pass the curved wall of the gib groove 26. Further, since the maximum distance from the bottom of the slot 12 to the gib 21 measured perpendicular to the bottom of the slot is less than the largest diametral dimension of the needle, the needle-shank cannot be inserted in any position other than the correct position.

Another modification of my invention is shown in Figs. 8 and 9, wherein a needle 15 having a shank 23', of generally pentagonal cross-section, is used. The various parts of the clamp are the same as the clamp described above and have been identified by the same numerals, except that a gib 21' formed with a V-shaped groove 26' replaces the gib 21. The device functions as previously described above, with the maximum distance obtainable between the bottom of the slot and the gib, measured perpendicular to the bottom of the slot, again being limited to a distance less than the width d of the needle-shank 23. It is, of course, apparent that the clamp may be readily adapted for use with needles of various sizes and having shanks of various cross-sections.

From the foregoing description, it is apparent that the present invention provides a needle clamp which will receive a sewing needle in one position only. Further, when the needle is clamped in position, the needle is positioned to pass the loop-taker of the machine at the proper distance.

Having thus set forth the nature of the invention, what I claim herein is:

the advantages of my In combination, a sewing needle having a shank formed as-a slab-sided right circular cylinder having a major and a minor diametral cross-sectional dimension; and a sewing needle clamp comprising, a needle-bar having a flatbottomed needle-shan'k-reoeiving slot formed in one end, said slot being of substantially the same width as the said major diametral dimension of said needle, a movable needle-clamping member cooperating with said slot and provided with a groove to receive said shank and shaped to conform to the curved portion of said shank, means limiting the movement of said member crosswise of said References Cited in the file of this patent UNITED STATES PATENTS 464,013 Di'ehl Dec. 1, 1891 1,697,424 Greenwood Jan. 1, 1 929 1,896,047 Grieb Jan. 31, 1-933 

